NAME

       pmem2_get_flush_fn() - get a flush function

SYNOPSIS

              #include <libpmem2.h>

              typedef void (*pmem2_flush_fn)(const void *ptr, size_t size);

              struct pmem2_map;

              pmem2_flush_fn pmem2_get_flush_fn(struct pmem2_map *map);

DESCRIPTION

       The  pmem2_get_flush_fn()  function  returns a pointer to a function responsible for efficiently flushing
       data in the range owned by the map.

       Flushing data using pmem2_flush_fn does not guarantee that the data is stored durably by the time it  re‐
       turns.   To  get  this guarantee, application should either use the persist operation (see pmem2_get_per‐
       sist_fn(3)) or follow pmem2_flush_fn by a drain operation (see pmem2_get_drain_fn(3)).

       There are no alignment restrictions on the range described by ptr and size, but pmem2_flush_fn may expand
       the range as necessary to meet platform alignment requirements.

       There is nothing atomic or transactional about pmem2_flush_fn.  Any unwritten stores in the  given  range
       will  be  written,  but  some stores may have already been written by virtue of normal cache eviction/re‐
       placement policies.  Correctly written code must not depend on stores  waiting  until  pmem2_flush_fn  is
       called to be flushed – they can be flushed at any time before pmem2_flush_fn is called.

       If  two  (or more) mappings share the same pmem2_flush_fn and they are adjacent to each other, it is safe
       to call this function for a range spanning those mappings.

RETURN VALUE

       The pmem2_get_flush_fn() function never returns NULL.

       The pmem2_get_flush_fn() for the same map always returns the same function.  This means that it’s safe to
       cache its return value.  However, this function is very cheap (because it returns a  precomputed  value),
       so caching may not be necessary.

SEE ALSO

       pmem2_get_drain_fn(3), pmem2_get_persist_fn(3), pmem2_map_new(3), libpmem2(7) and <https://pmem.io>